0987467425 {213691a2} jump start rails get up to speed with rails in a weekend hawthorne 2013 08 22

JUMP START RAILS
BY ANDY HAWTHORNE


ii

Jump Start Rails
by Andy Hawthorne
Copyright © 2013 SitePoint Pty. Ltd.
Product Manager: Simon Mackie

English Editor: Paul Fitzpatrick

Technical Editor: Glenn Goodrich

Cover Designer: Alex Walker

Notice of Rights
All rights reserved. No part of this book may be reproduced, stored in a retrieval system or transmitted
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However, the information contained in this book is sold without warranty, either express or implied.
Neither the authors and SitePoint Pty. Ltd., nor its dealers or distributors will be held liable for any
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Rather than indicating every occurrence of a trademarked name as such, this book uses the names only

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Published by SitePoint Pty. Ltd.
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ISBN 978-0-9874674-2-3 (print)
ISBN 978-0-9874674-3-0 (ebook)
Printed and bound in the United States of America


iii
About Andy Hawthorne
Andy is a freelance writer and web developer from Coventry, England. He has spent 12 years
as a web developer, and still likes trying new web coding technologies.

About SitePoint
SitePoint specializes in publishing fun, practical, and easy-to-understand content for web
professionals. Visit to access our blogs, books, newsletters, articles,
and community forums. You’ll find a stack of information on JavaScript, PHP, Ruby, mobile
development, design, and more.

About Jump Start
Jump Start books provide you with a rapid and practical introduction to web development
languages and technologies. Typically around 150 pages in length, they can be read in a
weekend, giving you a solid grounding in the topic and the confidence to experiment on
your own.

To my wife Mary— without her
never-failing love and support I'd
never get anything finished. And
to my Dad, who inspired me to
write in the first place.



Table of Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Who Should Read This Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Conventions Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Code Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Tips, Notes, and Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
Supplementary Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
Do you want to keep learning? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv

Chapter 1

Getting on Rails . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Do I need to know Ruby? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
What You'll Need . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
The Rails Stack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Rails and MVC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Installing Rails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Installing Rails on Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Installing on GNU Linux . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Installing Rails on Mac OS X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Some Other Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
rbenv . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Databases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Installing Ruby Gems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
A Word about Editors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Chapter 2

Starting an App . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Data First? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17


viii
Hello, World . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
A Simple App . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
The Project Folders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Generators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Generating a Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Some Notes About the Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Layouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Template Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Setting the Default Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Creating a Route . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Some Linking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Some Styling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Putting up Some Scaffolding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Generating a Scaffold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Active Record Validations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Test Driven Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
The Environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Tests Rails Has Already Generated . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Fixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Unit Testing Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Creating a Layout with Bootstrap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Install the Gem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Connect the Bootstrap Assets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Refining the Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Some Notes about the Rails Asset Pipeline . . . . . . . . . . . . . . . . . . . . . . . . 53
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Chapter 3

Working with Data . . . . . . . . . . . . . . . . . . . . . . 57

Starting the App . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
A Little Bit of Planning  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62


ix
Generating a Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Adding Some Validation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Adding a Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Adding Another Resource . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Creating an Association . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Some Rails Routing Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Adding a Test for Routes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Installing ActiveAdmin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Chapter 4

Creating an ActiveAdmin
Resource . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

83

Creating Admin Functionality Manually . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Creating a New Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Showing Pages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Creating Resources with ActiveAdmin . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Back to the Dashboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Editing the Pages Listing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
A New Resource . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
An Additional Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Adding Recent Posts to the Dashboard . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Controlling Fields on the Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Extra Functionality with Scopes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

Chapter 5

Adding More Features . . . . . . . . . . . . . . . . 109

The FriendlyId Gem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Managing Metadata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Uploads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

x
Installing the Gem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Using the Generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Creating an Uploads Folder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Updating the Post Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Uploading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Displaying Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Creating Thumbnail Images on the Fly . . . . . . . . . . . . . . . . . . . . . . 122
Uploading to S3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Creating a Layout with Bootstrap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
A Custom Helper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
Changing the Posts Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
Updating the Navigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Controlling Images in the Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

Chapter 6

Deploying to Heroku . . . . . . . . . . . . . . . . . . . 141

Using Partials to Add a Twitter Feed . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
A Dash of CoffeeScript . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Watch out for Those Turbolinks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
Adding the Portfolio (or Other Content) Section . . . . . . . . . . . . . . 151
Deployment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
Hello, Heroku . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Deployment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Working with Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
Adding a Custom Domain Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

Finally... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166


Preface
Ruby on Rails was created in 2003 by David Heinemeier Hansson. Since then it has
been extended by more than 21,000 contributors.
Rails was always intended to make web development a much slicker process than
was previously available with other technologies. It doesn't require thousands of
lines of code to get common functionality built into your apps. Rails uses the concept
of "convention over configuration", meaning that many of the common tasks we do
when developing web applications are covered quickly and easily.
It is true to say that Rails has a steeper learner curve than, say, your average PHP
framework. However, the effort to learn it is certainly worth it. I doubt that you will
ever fully go back to choosing other technologies over Rails where it makes sense
for the app you are building.
The Ruby programming language is a delight to work with, too. It's what Rails is
built on, and it offers a powerful set of features for all sorts of programming tasks,
not just those for the Web.
This is a short book, designed to give you a "jump start" with Rails. I've based it on
my own experiences of building a production Rails app for the first time. Hopefully,
like me, you will come to enjoy the slick, efficient web development experience
that Rails provides.

Who Should Read This Book
Developers seeking a rapid introduction to Rails. You'll need to know HTML and
CSS, and experience with other programming languages would be useful.

Conventions Used
You’ll notice that we’ve used certain typographic and layout styles throughout this
book to signify different types of information. Look out for the following items.

Code Samples
Code in this book will be displayed using a fixed-width font, like so:


xii

A Perfect Summer's Day

It was a lovely day for a walk in the park. The birds
were singing and the kids were all back at school.

If the code is to be found in the book’s code archive, the name of the file will appear
at the top of the program listing, like this:
example.css

.footer {
background-color: #CCC;
border-top: 1px solid #333;
}

If only part of the file is displayed, this is indicated by the word excerpt:
example.css (excerpt)

border-top: 1px solid #333;

If additional code is to be inserted into an existing example, the new code will be
displayed in bold:
function animate() {
new_variable = "Hello";
}

Also, where existing code is required for context, rather than repeat all the code, a
⋮ will be displayed:
function animate() {
⋮
return new_variable;
}

Some lines of code are intended to be entered on one line, but we’ve had to wrap
them because of page constraints. A ➥ indicates a line break that exists for formatting
purposes only, and should be ignored.


xiii
URL.open(" />
Tips, Notes, and Warnings
Hey, You!
Tips will give you helpful little pointers.

Ahem, Excuse Me …
Notes are useful asides that are related—but not critical—to the topic at hand.
Think of them as extra tidbits of information.

Make Sure You Always …
… pay attention to these important points.

Watch Out!
Warnings will highlight any gotchas that are likely to trip you up along the way.

Supplementary Materials
/>The book’s website, containing links, updates, resources, and more.

/>The downloadable code archive for this book.
/>SitePoint’s forums, for help on any tricky web problems.


Our email address, should you need to contact us for support, to report a problem, or for any other reason.


xiv

Do you want to keep learning?
You can now get unlimited access to courses and ALL SitePoint books at Learnable
for one low price. Enroll now and start learning today! Join Learnable and you’ll
stay ahead of the newest technology trends: .
Once you’ve mastered the principles of Rails, challenge yourself with our online
quiz. Can you achieve a perfect score? Head on over to
/>

Chapter

1

Getting on Rails
Welcome to Jump Start Rails! If you've come to Rails from another server-side coding
technology such as PHP, you are in for a treat. Rails offers a slick and efficient
coding experience for web developers, and was created with built-in solutions to
many of the common web development headaches.
Rails is open source and free to use, which means that you don't need to spend a
lot to get developing with it. In fact, the biggest outlay will probably be purchasing
an editor. We'll look at the options a little later in this chapter.
Rails was created in 2003 by David Heinemeier Hansson of 37 Signals1 fame. Since

then, it has seen rapid development by the Rails core team2, with over 2,000 contributors. Rails runs on the Ruby3 general purpose programming language, created
by Yukihiro “Matz” Matsumoto, in 1995.

1

/> />3
/>2


2

Jump Start Rails

Do I need to know Ruby?
You can certainly build simple Rails apps with a limited knowledge of Ruby. Many
developers tend to learn Ruby as they learn Rails. And as your knowledge and
confidence with Rails increases, you'll want to do more with it.
I've found that you can do this in incremental steps; it's entirely possible to build
a Rails app while you are still learning Ruby. The good news is that learning Rails
is a great experience, but learning Ruby is equally rewarding — especially if you
have come from another language like PHP, for example. Ruby is described on the
Ruby website4 as "a programmer's best friend" for a reason. So to really get into Rails
a good knowledge of Ruby will be required — eventually.
Ruby seems to be built for learning on the go—whenever you come across an obstacle,
the answer is never far away. Ruby Docs5 will help enormously with this.

What You'll Need
Ruby on Rails6, like many other web coding technologies, requires some setting up
on your system first. It's not too scary, though, and since this book covers Rails 4.0,
we only have to be concerned with setting up to use the latest versions.

Rails isn't Ruby. It's built using Ruby, and you use Ruby to build Rails applications.
As such, it needs to be present on your system for Rails to run. Happily Ruby is
available to run pretty much everywhere.

The Rails Stack
There are several components that make up the Rails stack. Obviously Ruby is one
component, the other main one being a database of some kind.
During the process of guiding you through installing Rails in this chapter, I'll mention
PostgreSQL7 and Ruby Version Manager (RVM)8. Technically neither are essential
requirements; it's just that they are common tools used in creating a Rails stack.
4

/> />6
/>7
/>8

5


Getting on Rails
RVM is a sandboxed way to install numerous versions of Ruby on your system, all
without affecting any system configuration files. It's available for Unix-based systems,
and as part of an installer9 for Windows.
If you create a Rails project without specifying a database, one will be created anyway. It'll be a SQLite database10, and will serve very well for your initial Rails investigation. However, in Chapter 6, we'll be deploying to Heroku11, and that requires
a PostgreSQL database12. As such, we'll be making PostgreSQL part of our Rails
stack too.

Rails and MVC
The Rails framework is based on the Model View Controller (MVC) design pattern.
No doubt you'll have heard of it if you've already spent time around web development. The truth is that, with Rails, there are real advantages to be had from MVC.

A few of these advantages are:
■ the ability to keep application logic (or business logic, if you prefer) separate
from the user interface
■ Don't Repeat Yourself (DRY) capability. The term DRY also applies in all forms
of web and software development. It's a concept where the objective is to only
write one piece of code to perform a particular task. You'll see this in action as
we begin to build our main app
■ a clear pattern for where each type of code should be stored within the application
Rails uses MVC like this:
■ Models are used mostly for setting the rules for interaction with database tables.
Normally, you would have one model per database table.

9

/> />11
/>12
/>10

3


4

Jump Start Rails
■ Views are HTML files with Ruby embedded to perform tasks for the presentation
of data. Views are the user interface   the part of your app with which the user
interacts.
■ Controllers are the components that decide how to respond to user requests.
They are responsible for coordinating responses too. You can think of them as
traffic police directing requests and responses around the application. It's important to understand that controllers are the only components that can speak

to models and views, as well as to our user's browser.

Installing Rails
Let's run through the basic process of getting Rails installed on Windows, Mac, and
Linux.

Installing Rails on Windows
I'm going to stick my neck out here: If you intend to work seriously with Rails, then
you might want to consider switching to a Unix-based operating system. The reason
is a practical one: You'll be spending a lot time on the command line with Rails.
You will also need to keep your Ruby gems up to date. This is all done via the
command line. The fact is, it's far easier to manage this stuff on a Unix system such
as Linux or Mac OS X. You could always run a Virtual Machine for your Railscoding projects, and I'll explain how to do that later in this chapter.
There are options for Windows users, and it's worth mentioning that huge efforts
are being made to make Ruby easier to work with on Windows.
If you are running Windows, there is now an easy solution for getting going with
Rails. The RailsInstaller13 has been provided by the team at Engine Yard, and it
takes the pain out of configuring Ruby and Rails manually. Simply download the
installer, run it, and away you go.
The installer includes all of the required gems and dependencies so that you can
start using Rails immediately. It even includes Git, the version control system,
widely used in the Ruby/Rails community.

13

/>

Getting on Rails

PostgreSQL Database

You can download the required software from the PostgreSQL14. It includes the
excellent pgAdmin tool—a graphical user interface for the database. You just need
to download and install the software and leave it at that. There is very little else to
do, as you will work with the database mostly via Rails.
When we get to deployment, I'll explain how you can import and export data between
your local PostgreSQL installation and the server running at Heroku.

Another Option for Windows Users
There is another way of setting up for Rails development on Windows―a virtual
machine (VM). It's a more involved process, but if you want to try Linux, this is one
way to do it.
For example, there is an excellent open source package available for Windows,
called VirtualBox15. VirtualBox provides you with the required base in which you're
free to create as many virtual machines as your system can handle. The idea is that
you install whichever flavor of Linux takes your fancy, install Ruby/Rails and the
associated requirements, and do your development in the VM, rather than on your
base system.
The advantage of this approach is that you don't have to install any of the required
components on your base system so, should anything go awry, you can simply delete
the VM and start again. Your base system is not affected in any way.
So, how do we do it? First, you'll have some downloading to do, and it certainly
helps if you have installed a Linux distribution (distro for short) before. Here are
the steps:
1. Download the ISO for your chosen Linux distro. I always store mine in a folder
called iso in my Home directory—it makes it easier to find when you create your
VM.
2. Download VirtualBox, and install it. This should prove to be just a normal installation, like any other software.

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3. Create a new VM, and select the ISO file you downloaded as the source. The ISO
file for various flavors of Linux can be found at their respective sites. For Ubuntu,
for example, head to Ubuntu's download page16 and follow the instructions to
download Ubuntu Desktop.
4. Once you have the ISO file, you can create a new VM and mount the ISO file,
which will boot into the installation program. Installing Ubuntu, for example, is
not difficult, but you may hit a speed bump or two. If you do, search the Web for
"installing Ubuntu on VirtualBox" for an avalanche of information.
There is an article on RubySource that demonstrates how to create a functional Rails
development environment using VirtualBox here17.
It's worth mentioning that you can install VirtualBox on most platforms, including
Linux. Once you have completed the above steps, you can jump in and install Rails
for Linux, which is covered in the next section.

Installing on GNU Linux
Most Linux distros come with Ruby installed, but there's a good chance that this
will be Ruby 1.8.7. While this is okay for older versions of Rails, we are using the
latest, Rails 4.0, so we need Ruby 1.9.3 or higher. And for the purposes of this book
we'll be using 2.0.
At the time of writing, there isn't a Rails Installer version for Linux, although there
is one planned. So for now, we'll have to do it ourselves. It's not difficult, though,
and as long as you're careful about installing the dependencies, you'll have a troublefree Rails installation running via RVM in no time.

The steps to install RVM vary from distro to distro. I'm going to cover installation
on the popular Ubuntu distro (version 12.10).
This routine will work on a fresh Ubuntu installation (so if you are installing in a
VM it'll work just fine), and I've also followed the same steps on older installations
of Ubuntu 12.10.

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Getting on Rails
Right, down to business. I've gone through this process with a clean Ubuntu installation running in a VM. We'll be doing everything via the Terminal, so fire it up,
and install curl:
sudo apt-get install curl

Likewise, we'll be needing Git for version control because that's how we deploy to
Heroku, and we need some essential tools to help us build some of the gems:
sudo apt-get install git-core build-essential

Next, we can go ahead and install RVM:
curl -L get.rvm.io | bash -s stable

When the installation completes, RVM provides you with essential information
about requirements and dependencies that need to be satisfied to run Ruby properly.
You can see what you need with:
rvm requirements

You'll get a list of dependencies that must be installed. The list will look something
like this:

Additional Dependencies:
# For Ruby / Ruby HEAD (MRI, Rubinius, & REE),
install the following:
ruby: /usr/bin/apt-get install build-essential openssl
➥libreadline6 libreadline6-dev curl git-core zlib1g
➥zlib1g-dev libssl-dev libyaml-dev libsqlite3-dev sqlite3
➥libxml2-dev libxslt-dev autoconf libc6-dev ncurses-dev
➥automake libtool bison subversion pkg-config

You can get all these dependencies installed in one hit in Terminal, by using aptget. So you would enter:

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sudo apt-get install build-essential openssl libreadline6
➥libreadline6-dev curl git-core zlib1g zlib1g-dev libssl-dev
➥ libyaml-dev libsqlite3-dev sqlite3 libxml2-dev libxslt-dev
➥autoconf libc6-dev ncurses-dev automake libtool bison
➥subversion pkg-config

Please note that the list of dependencies you see may not be the same as what's
shown here. Also, RVM does allow you to enable a setting that will automatically
handle the requirements (rvm autolibs enable) if you wish. For our purposes
we'll install them using apt-get.
Just to clear up any confusion here, you'll need to use sudo here, because the dependencies that are being installed are system wide. However, when we use RVM
to install gems a little later, you shouldn't use sudo. That's because RVM installs
on your local user account. That's why it's sandboxed and doesn't affect your system

Ruby.
Next, you need to make sure that RVM is being loaded as a function. The usual
method is to get on Terminal and enter:
source ~/.rvm/scripts/rvm

Re-start Terminal, and then enter:
type rvm | head -n 1

You should get: RVM is a function as a reply. If you do, great. If not, you'll need
to follow the instructions on the RVM web site18.

Installing Ruby
Now we can install Ruby. Enter:
rvm install 2.0.0

RVM will download and install Ruby version 2.0.0. Next, ensure your system is
using the newly installed version of Ruby as the default:

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Getting on Rails
rvm use 2.0.0 --default

We should be good to install Rails now:
gem install rails

That's it! Rails is now up and running.
We can also install PostgreSQL.This can be done via apt-get in Terminal, and you'll

also find it in the Ubuntu Software Centre. However, since you'll be needing the
development header files and their dependencies so that you can install the pg gem,
the easiest way to do it is to install everything you need via the Synaptic Package
Manager.
That can be installed via the Ubuntu Software Centre, as shown in Figure 1.1.

Figure 1.1. Ubuntu Software Centre

Then, via Synaptic, you can install all the components you need just by searching
for them: PostgreSQL itself, a file called postgresql-server-dev-9.1, and pgAdmin,
the GUI tool for working with PostgreSQL.

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Installing Rails on Mac OS X
Macs come with Ruby installed already. The only problem is, Rails needs at least
Ruby version 1.9 or higher to run and your Mac (yes, even one running Mountain
Lion) comes with Ruby 1.8.7. That's the bad news.
The good news is, Engine Yard have made a version of RailsInstaller19 for Macs too.
Even better, it installs in a sandbox so it has no effect on your system Ruby. All you
need to do is download the .DMG file and install it as you would any other Mac
software.
RailsInstaller provides you with everything you need to start building Rails apps.
Just keep in mind that the Installer adds RVM to your system so that you can easily
run different versions of Ruby, and different isolated sets of gems (called, unsurprisingly, "gemsets"). As a beginner, you may not see any advantage in that, but trust

me, if you've tried installation in other ways, the resulting pain is not nice at all.
You also get another treat with RailsInstaller. It comes in the shape of the JewelryBox,
which is shown in Figure 1.2. It's a graphical user interface for managing the Rubies
and associated gem sets you have on your system.

Figure 1.2. RailsInstaller JewelryBox

There are two kinds of experiences when installing gems via this set-up: hellish or
easy! To avoid the hellish option, you'll be needing some compilers.

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Getting on Rails
For OS X Mountain Lion you need software from Apple called XCode20. It's available
on the Mac App Store21, is free (although the download will suck up several gigabytes
of data), and installs just like any other software. You'll also need the command
line tools. You can use these if you are a member of the Apple developer community
as a separate download. Or, you can install them directly from within XCode. You'll
find the option to do so from the preferences panel (Preferences > Downloads >
Components > Install), as shown in Figure 1.3.

Figure 1.3. XCode command line tools

You can install just RVM without the RailsInstaller. RVM and its gemsets help you
jump between Ruby versions for your Ruby applications. XCode gives you the tools
that you need to compile those gems that require compilation when installed. If it
seems a bit convoluted right now, rest assured, it will get clearer as you play with

Ruby and Rails more.

Homebrew
If RVM helps you manage your Ruby-based dependencies (meaning, gems),
Homebrew helps you manage those dependencies outside of Ruby. One such dependency is PostgresSQL, which I mentioned earlier.
Homebrew refers to itself as "the missing package manager for OS X", and it's a good
description.
We are planning to build an app and deploy it to Heroku. For that, you'd be well
advised to get used to working with PostgreSQL. And to install that, we really need
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